Across 647 ranked games on patch 16.21 in Master and above, Twitch mains win 56.6% of their games in the bot lane.
Their most common build appears in 37.4% of those games and wins 59.5% of its 242 games.
It starts 
two Health Potions and 
Doran's Bow, completes 
The Collector, 
Fiendhunter Bolts, 
Infinity Edge and 
Lord Dominik's Regards in that order, and takes 
Berserker's Greaves.
Three other builds are played often enough in the bot lane to be measured on their own.
In the bot lane, Twitch mains fare best against 
Tristana (won 78.9% of 19 games), 
Jhin (won 68.3% of 41 games) and 
Lucian (won 70.6% of 17 games).
Their hardest matchups, the champions that counter Twitch, are 
Kai'Sa (won 37.5% of 40 games), 
Yunara (won 43.5% of 23 games) and 
Miss Fortune (won 45.0% of 20 games).